A study on novel electrostatic suspension system using piezo actuators

A study on new type of electrostatic suspension of silicon wafer, featuring ldquousing piezo actuators to control the positions of movable electroderdquo, has been reported. A novel aspect of this system is movable electrodes are used instead of stationary electrodes utilized in previous suspension system. By using a rapid deformation of the piezoelectric (PZT) actuator, the movement of the movable electrodes which are supplied by constant voltage is controlled. As a consequence the electrostatic forces are controlled by varying the capacitance formed by the movable electrodes and the suspended object. In this paper, a brief review of basic principles is presented. This is followed by a description of the structure of a prototype mechanism, including electrode and mechanical amplifier design, dynamic model of system, and the position feedback control method. Simulation and experimental results, which demonstrate completely suspension of 4-inch silicon wafer without any mechanical contact, are also presented.